1. Field of the Invention
The present invention relates generally to multi-fiber ferrules that more easily make physical contact in a connector system and a method of evaluating the multi-fiber ferrules, and, more particularly, to ferrules with optical fibers having a particular optical fiber tip radius and modulus of elasticity and a method for determining these characteristics.
2. Technical Background
Multi-fiber, monolithic ferrules are used in a vide variety of optical interconnect applications, including bulkhead feed-through connectivity, optical back planes, and outside feed plant passive optical networks. The typical MT ferrule is comprised of at least one fiber array with up to twelve 125 micron diameter fibers on a 250 micron centerline spacing. The MT ferrule has rectangular cross section of 2.4 millimeters by 6.4 millimeters and depth of 8 millimeters. The ferrules are generally molded from a highly glassed-filled, thermoplastic or thermoset resin, which combines the durability and stability required of a connector with the precision necessary to maintain low-loss single mode core-to-core alignment across multiple fibers. Other single row ferrules with four, eight, or twelve fibers are the most common, multi-row MT ferrules with up to 72 fibers being readily available. This high density interconnect package offers a compact, convenient means for quickly and effectively distributing large numbers of optical fibers. To assure precision alignment between two mating MT ferrule-based connectors, a non-interference, dual guide pin and hole system is used. One connector in the pair typically houses both guide pins while the mating, unpinned connector ferrule receives the guide pins when mated. The pinned and unpinned ferrules have identical geometries.
In order to establish a reliable, dry, low insertion loss, and low reflectance junction, physical contact between each fiber tip is imperative. Even with very accurate core-to-core alignment, power loss from Fresnel effects, which are associated with gaps between fiber tips, will not meet the requirements of today's WDM and Passive Optical Network applications. To achieve a physical contact, the ferrule and face is prepared such that the fiber tips are protruding from the ferrule surface.
It would be desirable therefore to provide multi-fiber ferrules in which all of the optical fibers make physical contact with the other optical fibers in a connector system with less force on the multi-fiber ferrules and the connector system and a method for determining which multi-fiber ferrules will most likely achieve that contact before they are installed into the system.